CD8A and colorectal carcinoma: The infiltration level of CD3+ or CD8+ cells classifies tumors as “immune hot” (high-infiltrated) or “immune cold” (non-infiltrated) (ref. [9–11]), and it was reported that the status of tumor-infiltrating lymphocytes is a better prognostic index than the TNM system for predicting survival outcome of CRC patients (ref. [12, 13]).